Are you using an adapter to read the SD card? Have you been using emulator software on your PC? If you have, I would recommend you to uninstall it and check again. How does the card appear in Disk Management?

Try the SD card on another PC. Update your anti virus software and do a complete scan.

SD Memory cards are read through external card reader [I have not had any trouble with this before] SD card displays as drive F: G: H: and I:' Properties of SD Card show capacity Full; all VRT apps used will not access the SD card, Any other PC..displays the same problems..multiple drives...no access...capacity full. Cards were last written on XP OS. am now using OS win.7